[EM] One more thought on Arrow

Alex Small alex_small2002 at yahoo.com
Sun May 15 10:20:55 PDT 2005

Given that IIA is incompatible with Pareto and non-dictatorship (i.e. impossible for any realistic public election method), from a practical perspective, IIA is a worthless criterion.
So the value of Arrow's Theorem is not simply that it proves IIA is impossible.  It is that he shows that:
1)  Seemingly simple properties can be impossible to satisfy, indicating that election methods can be subtle and complicated things
2)  Some of these subtleties can be addressed by general statements that transcend any particular method, meaning that election methods need not be studied method-by-method.  Sure, there's a place for that approach, but that approach can be supplemented and informed by a more general analysis.
P.S.  Here's another very general theorem:  When both participants in a flame war insist that they are merely defending themselves against the other guy's unwarranted attacks, then the number of messages posted in that flame war shall diverge as time goes to infinity.  The proof shall be supplied by people on this list.

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